The invention relates to the precision machine-building industry and can be used as a gear for creating an extra-precise linear drive in the machine-tool industry, metrology, optics and electronic industry.
Known is a magnetic screw gear comprising a cylindrical permanent magnet having helicoidal magnetization, the magnet being placed in a steel housing, and a screw with a spiral thread being made from ferromagnetic material and placed inside a nut with an air gap (International Conference on Micromechatronics for Information and Precision Equipment, Tokyo, Jul. 20-23, 1997).
The disadvantages of the known magnetic screw gear are low rigidity and low maximal carrying ability, since it is impossible to provide a sharp boundary between magnetized and non-magnetized sections of the cylindrical magnet.
Known is a magnetic screw gear comprising a screw and a nut interacting each other via an air radial gap, a permanent magnet and threaded pole pieces are mounted within the nut. Thread grooves of the screw and nut are filled with a non-magnetic material, the screw and nut having thread sections made from a ferromagnetic material, and radial openings being made in the nut or screw in order to supply a compressed fluid medium to the gap between the screw and the nut (USSR Certificate of Authorship No 1219850, Int. Cl. F 16 H 25/24, 1986).
The above described technical solution is the closest one to the invention according to a generality of problems being solved, and is chosen as the prior art.
However, the known magnetic screw gear has an insufficient kinematical accuracy and gear rigidity, as well as a technologically complex embodiment and large overall dimensions.
Technical result of the invention is in creating a contactless magnetic screw gear having an increased kinematical accuracy and gear rigidity with small overall dimensions.
Moreover, a saving of scarce materials is provided, and an adaptability to manufacture is increased when producing.
The essence of the invention consists in that a new contactless magnetic screw gear (CMSG) is created.
According to the first variant, the CMSG comprises a screw and a nut interacting each other via a radial gap, a permanent magnet and threaded pole pieces are mounted within the nut, the screw thread ridges being made from a ferromagnetic material, and the screw thread grooves and pole piece thread grooves being filled with a solid non-magnetic material. In the nut are made supplying channels intended for supplying a compressed fluid medium to the radial gap between the screw and the nut.
According to the first variant, the distinctive features of the CMSG are in introducing two magnetic circuits made in the form of coaxial rings, two aerostatical throttle units placed from two sides at the nut edges, two start rings mounted on the end faces of the nut, and a non-magnetic ring distance piece. The permanent magnet is made in the form of the ring magnetized along the axis of the nut and is mounted between magnetic circuit end faces faced each other, the pole pieces are made in the form of sleeves each being rigidly connected to the internal surface of the corresponding magnetic circuit, the non-magnetic ring distance piece is mounted between internal end faces of the pole pieces within the permanent magnet ring. Every aerostatical throttle unit is mounted in recesses of the magnetic circuit, adjoins the end face of the corresponding pole piece and is connected to the supplying channel formed by an opening made in the magnetic circuit.
The aerostatical throttle unit comprises an aerostatical throttle element, at least two ring separating grooves joined with a cross-over axial groove, the aerostatical throttle element being connected to the supplying channel through the ring separating grooves.
The aerostatical throttle element has three structural embodiments:
in the form of a ring from a porous material;
in the form of a ring with openings which have nozzles mounted therein;
in the form of calibrated slots.
According to the second variant, the CMSG comprises a screw and a nut interacting each other via a radial gap, a permanent magnet and threaded pole pieces are mounted within the nut, the screw thread ridges being made from ferromagnetic material, and the screw thread grooves and pole piece thread grooves being filled with a solid non-magnetic material. In the nut are made supplying channels intended for supplying a compressed fluid medium to the radial gap between the screw and the nut.
According to the second variant, the distinctive features of the CMSG are in introducing two magnetic circuits and N double length magnetic circuits made in the form of coaxial rings, N double length pole pieces, N permanent magnets, (N+1) non-magnetic ring distance pieces, where Nxe2x89xa61, two aerostatical throttle units placed from two sides at the nut edges, and two start rings mounted on the end faces of the nut. The nut is provided with a housing made from a non-magnetic material. The pole pieces and N the double length pole pieces are made in the form of sleeves each being rigidly connected to the internal surface of the corresponding magnetic circuit and N double length magnetic circuits. The permanent magnets are made in the form of the rings magnetized along the axis of the nut from the materials differing by a coercive force value, said permanent magnet being mounted behind the end face of the first magnetic circuit, and N-th one of the introduced permanent magnets being mounted behind the end face of the N-th double length magnetic circuit.
First one of the (N+1) non-magnetic ring distance pieces is mounted between internal end faces of the pole piece and the first double length pole piece inside the first permanent magnet ring, and every N-th non-magnetic ring distance piece is mounted after N-th double length pole piece inside the N-th permanent magnet ring.
Every aerostatical throttle unit is mounted in a recesses in the housing between the end faces of the corresponding pole piece and the start ring, and is connected to the supplying channel being formed by an opening made in the nut housing.
The screw is provided with an axial opening being hollow or filled with a bar from a non-magnetic material.
According to the third variant, the CMSG comprises a screw and a nut interacting each other via a radial gap, the screw thread ridges being made from a ferromagnetic material, and screw thread grooves being filled with a solid non-magnetic material, in the nut are made supplying channels intended for supplying a compressed fluid medium to the radial gap between the screw and the nut.
According to the third variant, the distinctive features of the CMSG are in introducing two aerostatical throttle units placed from two sides at the nut edges, two start rings and a ring thin-walled insert from a ferromagnetic material, the nut being provided with a housing made from a non-magnetic material, with which housing the ring insert being rigidly connected.
A multiple-start thread is made in the ring insert through its whole thickness, the thread grooves filled with a hard magnetic material form the helicoidal permanent magnets with the axial magnetization, the permanent magnets of even and odd starts of the thread being made from a material differing by a coercive force value, and magnetization directions of adjacent permanent magnets being opposite. A height of the helicoidal permanent magnets is less than a depth of the thread grooves for a thickness of a protective layer made from a non-magnetic material.
The start rings are mounted on the end faces of the nut, every aerostatical throttle unit is mounted in a recesses in the housing, adjoins the start ring and is connected to the supplying channel formed by an opening made in the nut housing, and the screw is provided with an axial opening being hollow or filled with a bar from a non-magnetic material.
The aerostatical throttle units and aerostatical throttle elements in the second and third variants of the CMSG have the same structural embodiment as in the first variant.
According to the fourth variant, the CMSG comprises a screw and a nut interacting each other via a radial gap, a permanent magnet and threaded pole pieces are mounted within the nut, the screw thread ridges being made from a ferromagnetic material, and the screw thread grooves and pole piece thread grooves being filled with a solid non-magnetic material. In the nut are made supplying channels intended for supplying a compressed fluid medium to the radial gap between the screw and the nut.
According to the fourth variant, the distinctive features of the CMSG are in introducing two magnetic circuits made in the form of coaxial rings, two aerostatical throttle units placed from two sides at the nut edges, two start rings mounted on the end faces of the nut, and a non-magnetic ring distance piece. The permanent magnet is made in the form of the ring magnetized along the axis of the nut, and is mounted between magnetic circuit end faces faced each other.
The pole pieces are made in the form of sleeves each being rigidly connected to internal surface of the corresponding magnetic circuit, the non-magnetic ring distance piece is mounted between internal end faces of the pole pieces within the permanent magnet ring, in which ring distance piece a T-shaped channel and a ring separating groove are made.
Every aerostatical throttle unit, through the radial gap between the screw and the nut and through the ring separating groove, is connected to the supplying channel formed by a radial opening made in one of the magnetic circuits and aligned with the T-shaped channel.
The aerostatical throttle unit in the fourth variant of the CMSG is made in the form of a ring slot formed by a cylindrical section of the internal surface of the start ring and a screw surface, a height of the ring slot being less than the radial gap between the screw and the nut.